Elemene is a natural medical substance extracted firstly in China from the rhizomes of Wen Yu Jin (Curcuma wenyujin), a plant from Zingiberaceae, also known as wenchow turmeric rhizome, serving as an anticancer agent with a novel structure. Elemene is found extensively in a wide variety of Traditional Chinese herbs, such as Radix ginseng, Largehead atractylodes rhizome, Syzygium aromaticum, Chloranthus fortunei, Chioranthus multistachys, Commiphora myrrha, Divaricate saposhnikovia Root, etc. Chemical name for elemene is 1-methyl-1-vinyl-2,4-disopropenylcyclohexane, with the molecular formula: C15H24. Four isomers are found in the elemene: α-elemene, β-elemene, γ-elemene and Δ-elemene, with the primary component of the anti-tumor plant-medicament elemene being β-elemene. The chemical structural formula for the elemene is as follows:

Many literatures have reported the methods for preparing elemene, which generally comprise extracting and refining elemene from the plants such as Zedoary turmeric, etc.; or isolating elemene directly from Zedoary turmeric oil. Such methods are described in Chinese patent applications: CN1686975A, CN1651366A and CN1200266A.
The elemene had been approved as a Chinese new drug of national Class II in December, 1993. The anti-cancer efficacy of the elemene had been verified by the Ministry of Health of the People's Republic of China in February, 1994. Elemene is the first anti-tumor plant-medicament in the world which contains no toxic groups such as epoxy, nitro, anthracene ring, benzene ring, etc. Thus, it has no toxicity, a mild adverse reaction, an established efficacy as well as an excellent price/performance ratio. Moreover, it had unique properties such as crossing the blood-brain barrier and the blood-bone barrier. Elemene is a volatile oil and thus exhibits stronger volatility and liposolubility. It is clinically used mainly in treatment of various cancers such as esophageal cancers, lung cancers, brain tumors, hepatocarcinomas, cervical cancers, cancerous chest, ascite, etc. The elemene emulsion injection made from elemene as feedstock has been used widely in clinics and exhibited good efficacy in clinical environments. Presently, there are two types of administration routes for elemene, i.e., injection and oral administration, and correspondingly two types of dosage forms, i.e., elemene injection and elemene oral emulsion. The elemene formulations in the art are all rapid-release formulations with frequent dosing times and a short biological half-life, thus leading to more significant fluctuation in the plasma concentration. Oral administration of elemene exhibits a significant first-pass effect and thus a low bioavailability. Intravenous administration of elemene is liable to induce local phlebitis, drug fever, thrombocytopenia, pain at the infusion site and digestive tract reactions. For the preparation of elemene formulations, see Chinese patent applications: CN1244389A, CN1508176A, CN1076613A, CN1507857A, CN101461793A, CN1221607A and CN1451377A. However, formulations disclosed in the above patents exhibit more significant adverse reactions when used clinically, and have disadvantages with respects of storage and anti-cancer activities.
Heretofore, there is no patent literature about research on an anti-tumor plant-medicament sustained-release tablet of elemene. Also there is no patent literature about use of elemene in a dosage form of a sustained-release tablet for treating conditions such as esophageal cancers, lung cancers, brain tumors, hepatocarcinomas, cervical cancers, cancerous chest, ascite, etc.